/Engine/Source/Runtime/GeometryCore/Public/Spatial/MeshAABBTree3.h
Find the triangle closest to P, and distance to it, within distance MaxDist, or return InvalidID Use MeshQueries.TriangleDistance() to get more information
virtual int FindNearestTriangle ( const FVector3d & P, double & NearestDistSqr, const [FQueryOptions](API\Runtime\GeometryCore\Spatial\IMeshSpatial\FQueryOptions) & Options ) const